From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9A311FD376C for ; Wed, 25 Feb 2026 16:08:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 09B7A6B00A3; Wed, 25 Feb 2026 11:08:37 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 073156B00A5; Wed, 25 Feb 2026 11:08:37 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EB75E6B00A6; Wed, 25 Feb 2026 11:08:36 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id D2C9E6B00A3 for ; Wed, 25 Feb 2026 11:08:36 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 7E2F813B5F1 for ; Wed, 25 Feb 2026 16:08:36 +0000 (UTC) X-FDA: 84483461832.18.0E5EE5C Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf13.hostedemail.com (Postfix) with ESMTP id BA9A820005 for ; Wed, 25 Feb 2026 16:08:34 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=r9gj3Soi; spf=pass (imf13.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1772035714; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=FFWSFvcs3OLl8e5i1Jd9VVYSUmxtFekcTUezinSfDio=; b=l0GCsN2i4cwiHpj6TYC4pinQgmPqJm4O9As/Lv19C+ObljjeRqw8X6XwrKjZ+LVLMl2HbP xTp8+QT0M+IfLN4Zv90WO3LQtVJwsnFLbuh6d0zmp6xsCVvLt9ndR0+zlLBO1zQXiQSejZ L67pRT6sMfzBaXbi2SCZ0Nnv0EGrUn0= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772035714; a=rsa-sha256; cv=none; b=EAeqyfyT2gTOC9T2KtQ3BVVWN5pRruAyeICWRwAOZvstg62yVdorKtl9gNlc9s2D5DLk5x Ka5BhU/P44+8+vAw5MpLQVUDEGaGPjUNHdb57puCyAJADPYMwL0WcA24dJPDCAI5RVucjX G7mfiErrf77i4OvtxiMY/JRLOXNa634= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=r9gj3Soi; spf=pass (imf13.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id E5C1C600AE; Wed, 25 Feb 2026 16:08:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DCD0DC116D0; Wed, 25 Feb 2026 16:08:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772035713; bh=MT1L7YBLKKqIK0OqXYMAqrJF0p22rKY9Fuu8MlKzILc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=r9gj3SoiOrfGytjtrhqCxDhEEhl8435Ek4kDJS9YBc5rkgjf26cCrnyVvPzJo2Eue GOYFmesqLiGv83qEyOqJyMvyyOh5aPvJ09mLhxoxxjm6OUyj3k39Rybm5R3Yhub9k8 pl2lhCGm7jBmlMuO9l1Dc/ddqDN2imj61JyDYjEo39rIxtSM5cyMFQWdzb+4KoEHxo Tj9Qte4nbZnYW0Q2+uZTXS+TlrXqW7OZESQWtZ/o8uZfJuxM6NbzZ3Quc9xrD70LW0 bmkPxUX11qKtNcJn/DmTz8xVfxHEYZvke4SP/YOkWklY2jwD+8y9Vqca3/mxrI9H6I YtUIOcGUE4Yiw== Message-ID: <6b5e14a9-751d-4a0d-9d53-b45a0ee5a4ed@kernel.org> Date: Wed, 25 Feb 2026 17:08:28 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] Revert "ptdesc: remove references to folios from __pagetable_ctor() and pagetable_dtor()" To: Matthew Wilcox , Axel Rasmussen Cc: Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260225002434.2953895-1-axelrasmussen@google.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: xir3usdgro7eo36yrmh1i6g3cbugk6on X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: BA9A820005 X-HE-Tag: 1772035714-719000 X-HE-Meta: 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 LqIFP3Jd ZbKutEzeuVVyBfvbMnoW/Zpx+L4blSoY91H0Wzo6bRFR9SywSMg7c5Sp+Zy6v798Cp57WPhNcrPKlWOCtVHUyMAGiXo9MCapfwH/o/Tk6qa/IaIochRQLoLhHRVkCM/oa1kVVOAOihlJamwAvfF98sIW40OGwCTV9EVTbsM+VFcVx1fuLqAVV9hONE1uhqV1T6/nrw3GXoNzK828FfOfeJN1xOxfI2ch52js1UTA+DrnIvIgrJsnioecqcwEk/gV/SyGEVED3SmN1q5zb26a1IUiumnmbx9BidUqHeTOn+FtfgDp75slEAe9cCA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2/25/26 17:03, Matthew Wilcox wrote: > On Tue, Feb 24, 2026 at 04:24:34PM -0800, Axel Rasmussen wrote: >> This change swapped out mod_node_page_state for lruvec_stat_add_folio. >> But, these two APIs are not interchangeable: the lruvec version also >> increments memcg stats, in addition to "global" pgdat stats. >> >> So after this change, the "pagetables" memcg stat in memory.stat always >> yields "0", which is a userspace visible regression. >> >> I tried to look for a refactor where we add a variant of >> lruvec_stat_mod_folio which takes a pgdat and a memcg instead of a >> folio, to try to adhere to the spirit of the original patch. But at the >> end of the day this just means we have to call >> folio_memcg(ptdesc_folio(ptdesc)) anyway, which doesn't really >> accomplish much. > > Thank you! I hadn't been able to get a straight answer on this before. > > You're right that there's no good function to call, but that just means > we need to make one. The principle here is that (eventually) different > memdescs don't need to know about each other. Obviously we're not there > yet, but we can start disentangling them by not casting ptdescs back to > folios (even though they're created that way). > > Here's three patches smooshed together; I have them separately and I'll > post them soon. Should we just apply + backport the revert for now and re-do it based on the revert? -- Cheers, David